Last summer the News, Portsmouth's unimaginatively titled local paper, published an interview with the Gosport Borough manager, Alex Pike. Introducing him with a warning that "many think him an annoying motormouth with an inflated ego", it contained a selection of self-promoting pronouncements. "I heard someone remark that I thought I was the José Mourinho of non-league football, but I've been doing it long before him," Pike said at one point, adding that "I haven't got into football to make friends".

Right now he has few enemies in Hampshire, with the possible exception of those who support Gosport's near-neighbours Havant & Waterlooville. Last month the Hawks were beaten 3-1 on aggregate in the FA Trophy semi-finals to earn Pike and his players a visit to Wembley, where on Sunday they will play the Conference Premier high-flyers Cambridge United.

Five years ago Gosport's league visit to Hayes attracted a crowd of just 27. The second leg of this year's semi-final derby brought 2,901 to Privett Park, and on Sunday they could have four times that number cheering them on in London. Even if the visit to Wembley ends with the resounding defeat most bookmakers are confidently predicting, the final will gild a golden period for Gosport, whose big day out caps a seven-year sprint up the football pyramid from the Wessex League – the ninth level of English football – via three promotions to the previously unexplored heights of the Conference South.

Strictly speaking Gosport's first ever visit to Wembley will come on Saturday, when the team will be shown around the ground before taking their places among the 85,000 watching Saracens play Harlequins. But their manager has been here before, with Wimborne Town in 1991-92, when the then 31-year-old's first full season in management culminated in a run to the FA Vase final, where they beat Guiseley 5-3. And if his ego is sizeable now, it must have been terrifying then.

"I was an arrogant man in 1992 and it all passed in a blur," says Pike. "I don't remember too much about it. I'm going to make sure I appreciate it this time. I remember after that match my chairman at the time coming on the team coach, and I'm all full of enthusiasm, and he said, 'If I was you I'd retire now because it's all downhill from here.' To a certain degree he's been proved right."

There will be no fourth promotion this season. Defeat to third-placed Sutton United on Tuesday pushed Gosport to 20th, just two off the bottom, albeit with between one and four games in hand on those around them. "The step up from the Southern League is the biggest I've seen. We've been hampered by the weather, plus the Trophy run," says Pike. "Since we qualified for the final, our experienced players have been managing their bodies. They're not going to put their foot in and get injured when we're about to go to Wembley. They realise they may never get this kind of opportunity again. I've got one player in my side who's 19. He started when he was 16, and since then he's had two promotions and now he's going to Wembley. He thinks it'll come along again next year."

Jamie Brown, Gosport's 32-year-old midfielder and captain, is certainly not taking the occasion lightly. "I've never even been to the new Wembley," he says. "As much as my last couple of clubs were brilliant, I think it's everyone's dream to play with a bunch of lads you can class as your friends, and then to achieve what we have – the promotions, and now the cup run – has just been unimaginable and amazing. We've all dreamed of playing at Wembley, just to see the arch will be incredible. I think we're all going to be nervous, when we're singing the national anthem, with the names on the back of our shirts and looking out at the crowd. But we're not going there to sightsee and enjoy the view, we're going there to win."

Whatever the odds, Cambridge's impressive league position hides some unexceptional form. The U's won 11 of their first 16 games as it took until November for anyone to beat them, but they have now won only two of their last 11 league matches. "I've always found it difficult to worry about the opposition," says Brown. "I'm not too interested in how good Cambridge are. I'd rather concentrate on what we need to do, and take it to them. We want to go there and give them a good game."

An upset is not beyond the realms of possibility, even if it might take all of Pike's self-proclaimed powers to earn it. "From outside looking in, it's an amazing achievement what he's done," says Brown. "Going up three stages and also reaching your second Wembley final is pretty amazing for any manager at any level. At one stage last year we were second bottom, and a lot of heads were down. But he's like a motivational speaker – one thing Pikey gives you is belief, and with belief you can achieve anything."